As New A Member As It Gets; I have New 29r Mt Bike; I Have MPIII Questions

[BikeSlob]

Hi I am a new member, just stumbled on this forum and company trying to decide what DIY kit to order.

I bought this bike for riding trails, yet I realize it would be great to motorize because of rough roads between work and home.
http://www.bikesdirect.com/products/gravity/fsx_29one.htm


Now I want to add an MPIII but I have some questions.
Since I want as much power and speed as (sanely) possible, which single battery configuration should I get?
And will an MPIII work on the above mentioned bicycle?

I read Super G's posting and Youtube on his Schwinn conversion and got really excited. http://goldenmotor.com/SMF/index.php?topic=4849.msg28253#msg28253

I am noticing that most examples on Golden Motor are rear mounted motors. Should I go this route? I know nothing, front wheel looks easier, but maybe too much torque.

Also, why would I need a "Speed Cassette" for the rear gears? Forgive my ignorance on this subject but the bike comes with 9 already back there.

Should I assume that I can't use this for riding mountain bike trails anymore?

And is it cheaper to buy from local dealer (kinda local: next state over) or order from factory and pay shipping?

I have a feeling I have more questions. But I know sooner or later, it's going to cost me less to get to work and be quicker than public transportation or car.

I invite all input. . . and appreciate this forum for existing.

[Morgen 3Eman]

Welcome, BikeSlob!

There are some very knowledgable folks on this site.  Alan is easily the top of the heap.   Gary is clearly an honest vendor who can be trusted.   Dealing with China seems to be problematic for many on this site. 

Anyway, I have no knowledge, only an opinion to share.  And it is a very strongly held opinion:  Front wheel drive on any vehicle is a horrible thing.   Weight transfers off the front wheel during acceleration, make wheel spin more likely, and rapid acceleration less likely.  Under braking, the opposite occurs, the weight shift to the front.  Which means the rear wheel can contribute less to the braking effort because it is likely to lock up and skid. 

Is there some packaging advantage to front wheel drive?  Absolutely.  But if packaging is more important to you than performance as a vehicle,  go get a Ford Transit Connect....

Did I mention I'm opinionated?

Personally, I have a MP3 with a 48VDC GM battery, and am very pleased with the performance now that I have replaced the internal controller.  (two of them fried on me in a few weeks)  Whatever you decide to do, if you choose an MP3, you will need torque arms to keep it from distorting the drop-outs. 

Have fun with it, and always wear a helmet.

TTFN,
Dennis

[BikeSlob]

Thanks Dennis.
Good info.
What controller are you using if the Magic Pie 3 one fried?
Is that a deal breaker? Should I look at Leaf Motors?

Cheers,
John

[Morgen 3Eman]

Hi John,

I think I bought one of the first 48V MP3s, and the problem was probably that the filter capacitors were only rated for 63 VDC, while a freshly charged battery could subject them to 56 VDC-  way to close to the rated value.  I suspect that using regen at high speed is what fried the caps.   In the intervening year, the complaints on the board about fried MP3 controllers has largely disappeared, but I wanted to be sure to mention it.  I don't remember anyone frying an MP3 on 36 VDC.    The physical design of the system is very clever, but the assembly quality was not as good as it could be.  I bought a Lyen controller and have had no problems since.  I have to state that the performance of the internal controller was great, it just didn't work for very long.  Uprating the filter caps to a higher voltage rating would be an easy production line change, and I wouldn't be surprised to find that is what happened.     

I have no hands on knowledge about Leaf, but suspect there will be displeased users there, too.  That was why I bought a GM.

You should consider doing a search of the board for information about spokes, torque arms, wiring, etc. to give yourself a better feel for what you are likely to need to build a great, reliable bike.  (Keep in mind that the internet only makes you and me taller, smarter and better looking-  some of the other guys are just posers fronting for the NSA:) )

TTFN,
Dennis

[BikeSlob]

ok, torque arm it is (or is that plural?).
going for back wheel, 700cc, 48VDC battery.
Need to go home and measure rear width of frame.

still mulling over buying locally or even from Canada.
no deals from the factory in China.

[Morgen 3Eman]

Just type "torque arms" into the search box above, and decide....You can see photos to help you with the installation and decision.  I fabbed my own swing arm, but I think the consensus would be to use two torque arms.   By the way, if they fit your particular installation, a pair of wrenches of a correct size will do the job nicely, and cheaply. 

From recent posts, selecting spokes is just as important.  I have a cast wheel, and thus nothing to share. 



TTFN,
Dennis

[Bikemad]

Also, why would I need a "Speed Cassette" for the rear gears? Forgive my ignorance on this subject but the bike comes with 9 already back there.

There is a big difference between the old style thread-on freewheels and newer type of splined cassettes:



Your nine speed rear wheel is more than likely fitted with a nine speed cassette that cannot simply be swapped over as the Magic Pie comes with a threaded boss to receive the gear cluster unit instead of splines.

It might be possible to fit either a Sunrace MFM90 13-32T or a DNP 11-32T Screw on nine speed freewheel unit with the aid of extra spacer washers, but only if your frame is capable of accommodating the additional axle width.

Alan
 

[BikeSlob]

Thank you Dennis, thank you Alan.

I see now exactly what you mean about the cassettes.

I think losing a couple gears is no big deal, for now, and probably easier to go with threaded boss etc.

But all of a sudden I have a new worry, and that is that I've heard you can't pedal these bikes without the
motor on. In other words, it has to be electric or not. Is there a way around this? I'm not thinking of riding across logs
but there are some nice rocky trails I wouldn't mind doing with this thing.

Would it be possible to switch out the rear tire--one with MP 3, the other with regular Mt Bike wheel in order to have a day without the motor?

The back measures 135mm so I believe that is what I want.

Alan, do you have an ebike business?

To summarize:
1--Is there anyway to preserve the bike for natural pedaling at the same time have the MP3 on it?

I am really grateful to your replies and input.

[Bikemad]

Alan, do you have an ebike business?

To summarize:
1--Is there anyway to preserve the bike for natural pedaling at the same time have the MP III on it?

Sorry John, I don't have my own ebike business, I just have a few own bikes equipped with GM motors:

Smart Pie:


This one is currently fitted with an MPII, but was originally fitted with one of the first Magic Pies:


This MPIII is still a work in progress:


I have ridden two of my bikes without a battery pack on several occasions while accompanying my wife on a leisurely ride, and the additional drag from the unpowered Magic Pie motors can be quite strong when pedalling at speeds over 10mph, however, it is not noticeable on the Smart Pie.

Swapping wheels is definitely a possibility, although there would be the additional hassle of removing the motor wiring harness and torque arms etc. and resetting the dérailleur limit stops to suit the different gear cluster.

Alan
 
 

[BikeSlob]

Thanks Alan.
I guess I'll buy another mt bike just for mt bike. or put the pie on my carbon fiber which doesn't
have any suspension springs.

Google Maps says it's 14 miles between work and home
17 miles if I take the Springwater Corridor, which is through woods and and fields.

So I am ripe for an ebike.

[BikeSlob]

I have another question. The choice of kits on www.goldenmotor.com only references the 48V10AH battery. What is the next step up in batteries or is there one? I'm thinking a little extra juice wouldn't hurt if I'm near max miles for the 10ah. I'm assuming this can all be programmed using USB and PC to coordinate battery size and motor.

I notice Leaf Motor has a 48V 12Ah Rack lithium ion battery for about the same price, including charger and metal case
http://www.leafbike.com/products/lithium-battery/48v-li-battery/48v-12ah-rack-lithium-ion-battery-851.html
* BMS(BATTERY MANAGEMENT SYSTEM) and 100V~240VAC 50/60Hz 1.8A Universal Charger Included
* Weight: 5.2Kgs
* Capacities: 12Ah
* Max Discharge Current: 50A
* Max Continuous Discharge Current: 30A
* Charging Cycles: >2000 times
* Reference Ranges(full electric mode): 50Km
* Dimensions: 325mm L × 150 mm W  × 84 mm H 

Package Content
1 x 48V 12Ah rack lithium ion battery
1 x 48V 100V~240VAC 50/60Hz 1.8A charger
Net weight: 6.3Kg (with charger + slippery plate + discharging wire)



Also, which cassette do I want, the 6 or 7 gear one? How can I tell or will either work.

[Morgen 3Eman]

Hi John,

DANGER<DANGER<DANGER to your wallet.  Find out the specific "lithium ion" battery chemistry they are using.  Some of them start fires rather easily.  Others don't respond well to improper charging.  My research led to LiFePo4 as the best choice for me, your needs may be different...

TTFN,
Dennis

[BikeSlob]

Thank you. I'm new at this.
So . . what is the next step up with a LiFePo4?
the DIY kit on golden only gives one 48V choice, the 10Ah.

[BikeSlob]

Another question?
Are the 6 and 7 gear cassettes the same width? I how would I even know which one to order? I was figuring mo' is betta', but just checking.